1. Field of the Invention
This invention relates to pumps and, in particular, to nonaerosol pump sprayers.
2. Description of Related Art
Noncontainer pressurizing pump sprayers commonly utilize an integral cylinder and plunger arrangement to generate pressure to expel liquid, such as insecticide and fertilizer from a container. Noncontainer pressurizing pump sprayers are desirable in that they do not utilize pressurized containers which must be handled carefully and at controlled temperatures to avoid the risk of explosion. Noncontainer pressurizing pump sprayers have a number of other advantages, including not using propellants which destroy the ozone and being relatively inexpensive.
There are two common varieties of noncontainer pressurizing pump sprayers: pump sprayers that are pressurized on the upstroke and pump sprayers that are pressurized on the downstroke. Pump sprayers that are pressurized on the downstroke typically utilize a return spring which biases the plunger upward after the pressurization stroke. These sprayers suffer from the drawback that it is often undesirable to store or ship the pump sprayer with the plunger in the up position. Accordingly, the pump sprayer is generally shipped and stored with the return spring in a compressed position, causing the spring to fatigue and begin to wear out prematurely. Likewise, in the event of the inadvertent release of the return spring, the plunger cannot be depressed without pressurizing the fluid in the container. In the case of insecticide or other toxic chemicals, this is often undesirable.
While pump sprayers that are pressurized by pulling the plunger upward have the advantage of not having the plunger being forced outward inadvertently, they too, suffer from a number of drawbacks. For example, once the plunger is drawn upward, it is generally not possible to lower the plunger without discharging fluid. As drawing the plunger upward creates a relatively large volume of pressurized liquid, this either requires that a relatively large amount of fluid be wasted or the device be stored with the plunger extending outward.
U.S. Pat. No. 4,174,055, to Capra, et al., discloses an alternative dispenser. The disclosed dispenser incorporates a plunger which pressurizes the fluid on the upstroke, but also is provided with a separate return spring and collar for purposes of lowering the plunger handle independently of the main plunger piston. While this arrangement has advantages, it is more complicated and expensive than other pump sprayer arrangements. Further, while the system provides for slow bleeding off of pressure, the sprayer remains in a pressurized state for some time. Significantly, this substantially increases the risk of inadvertent discharge of chemicals by adults or children who may come into contact with the device.
The present invention includes an apparatus and pump attachment particularly adapted to form a noncontainer pressurizing pump sprayer which overcomes the drawbacks of the prior art. The apparatus desirably includes an attachment having a pump sprayer which is pressurized on the upstroke, enabling the sprayer to be shipped and stored in a relaxed position. Importantly, however, the plunger is adapted to permit the plunger to be lowered and the apparatus depressurized without discharging fluid. Significantly, these advantages are provided in a apparatus which is particularly adapted to be inexpensively manufactured and includes few moving parts, to enhance reliability.
One aspect of the invention includes a pump attachment for a container that defines a neck. The attachment includes a body that defines an elongate chamber having a first end, a second end, and an interior wall that extends between said first end and said second end. A coupler is sized and shaped to secure the body to the neck of the container. A shaft extends through an opening in the first end of the chamber. The shaft defines an internal flow channel and is moveable within the body between a first position and a second position. A piston is reciprocally mounted within the chamber. The piston defines an outer annular surface that is sized and shaped to form a sealing engagement with the interior wall of the body. The piston further defines an inner annular surface in which the shaft is mounted such that the shaft can move independent of the piston between the first and second positions. The inner annular surface also includes a sealing surface to restrict the flow of fluid between the inner annular surface and the shaft. The piston separates the chamber into an upper portion above the piston and a lower potion below the piston. A biasing member is located between the piston and the first end of the chamber. A first valve is located at the second end of the body. The first valve is configured to permit the flow of fluid into the chamber and to restrict the flow of fluid out of the chamber. A second valve is also located at the second end of the body. The second valve is moveable between an open position configured to permit the flow of fluid out of said chamber and a closed position configured to restrict the flow of fluid out of the chamber. The second valve is further configured to be biased to the closed position. The attachment is configured such that when said the is moved to said first position the shaft moves the second valve from the closed position to the open position.
Another aspect of the invention is a pump attachment for a container that defines a neck. A body defines an elongate chamber having a first end, a second end, and an interior wall extending between the first end and the second end. A coupler is sized and shaped to secure the body to the neck of the container. A shaft extends through an opening in the first end of the chamber. The shaft defines an internal flow channel. A piston is reciprocally mounted within the chamber and is connected to the shaft. The piston defines an outer annular surface that is sized and shaped to form a sealing engagement with the interior wall of the body. The piston separates the chamber into an upper portion above the piston and a lower potion below the piston. An inlet valve is located at the second end of the body and is configured to permit the flow of fluid into the chamber and to restrict the flow of fluid out of the chamber. A biasing member is positioned between the piston and the first end of the chamber. A bleeder orifice is formed within the second end of the body.
Yet another aspect of the invention is a method of arming and disarming a spray apparatus that includes a container containing fluid and an attachment mounted thereto. The apparatus has a body that defines an elongate chamber, a shaft that extends through an opening in the chamber and defines an internal flow channel, a piston that is reciprocally mounted within the chamber, a first check valve, a second check valve and a biasing member. The shaft is moved in a first direction relative the body. The piston thereby moves in the first direction and draws fluid from the container into the chamber through the check valve and compresses the biasing member. The biasing member is permitted to force the piston against the fluid in the chamber in a second direction pressurizing the fluid. The liquid is released from the chamber though the internal flow chain the shaft. The shaft is moved in a second direction relative to the body. The piston opens the second check valve. The check valve permits the flow of fluid out of the chamber, thereby, depressurizing the fluid.